420 



A HISTORY OF FISHES 



common, and, in the case of the Goldfish {Carassius), abnormal 

 types originally appearing as mutations or "sports" have been 

 perpetuated by the Japanese breeders to become distinct races 

 or varieties. The grotesque "Pop-eye," the "Veil-tail," and 

 the remarkable "Lion-head" are familiar objects in aquaria 

 (Fig. 143), and represent monstrosities that have bred true to 



Fig. 143. DOMESTICATED FISHES. 



A. Veil-tailed variety of Goldfish (Carassius auratus) ; b. Pop-eyed variety ; 



C. Lion-headed variety. All x about ^ ; d. Mirror Carp, a cultivated variety of 



the Common Carp {Cyprimis carpio), x about \. 



type. Double-headed fry, or young fishes abnormally united 

 or incompletely divided, frequently occur in fish hatcheries, 

 but very rarely live beyond the stage at which the yolk-sac is 

 absorbed. These and other abnormalities of a like nature are 

 generally congenital in origin, but some may be due to accidents 

 to the young or adult fish. Fishes in general have little power 

 to regenerate lost parts, beyond reproducing the tips of the 

 fins and other superficial structures which may be injured or 



